WO2009101304A1

WO2009101304A1 - Method and device for shaping raised patterns in a planar sheet

Info

Publication number: WO2009101304A1
Application number: PCT/FR2008/001725
Authority: WO
Inventors: Arthur Lebee
Original assignee: Arthur Lebee
Priority date: 2007-12-18
Filing date: 2008-12-11
Publication date: 2009-08-20
Also published as: FR2924955A1; FR2924955B1

Abstract

The invention relates to a method and a device for making an embossed or pleated wall having a base pattern that includes two adjacent dihedrals, i.e. one concave and one convex, in which the outline of the surfaces defines a parallelogram while the edges lie as an extension of each other and have substantially collinear projections (D) in a horizontal plane, characterised in that it comprises printing an embossment blank on a planar strip (10) by stamping (11), in that the strip is subjected (12, 15) to a progressive reduction of the size thereof taken perpendicularly to the abovementioned planar projection of the edges down to a predetermined deformation-resistance threshold, and in that it comprises progressively unfolding (17), in a controlled manner, the strip thus deformed until a desired thickness is obtained.

Description

Method and device for the conformation of reliefs in a flat sheet

The present invention relates to a method for producing reliefs, folds or embossing in a flat sheet and a device for implementing this method.

BACKGROUND OF THE INVENTION The pleated or embossed structures have been known for a very long time. They come from artisanal manufacturing processes and are found mainly in the field of paper or fabric articles.

This technique has been transposed to the pleating or embossing of the flat sheets, in particular metallic foils, to produce, for example, the core of a sandwich structure sandwiched between two skin sheets, instead of a cellular core of the honeycomb or foil type. corrugated.

It does not appear that this transposition has led to industrial manufacture today, since no such product is present on the market.

To illustrate the state of the art, document FR-2.273.657 proposes a method for producing a pleated chevron structure from a web passing through stamping members to make a rough outline of the reliefs of the pattern. perform, followed by a series of movable members to complete the folds outlined by the die-casting members. The technique according to this document never came into existence. Another illustration of the state of the art is formed by the document US 2004/0102303 in which, starting from an initial stamping for a blank, the deformation (folding) is continued by forcing a compression of the band in an area where this band enters at a higher speed than it gets out. It happens therefore in this zone an accumulation of material which leads to the accentuation of the folds and consequently, to the accentuation of the pattern with a thickening of the product at the same time as a narrowing of the band. OBJECT OF THE INVENTION

The present invention relates to a method by which one can better control the formation of the pleated or embossed structure and in particular the regularity of the pattern that it comprises. For this purpose, the invention therefore firstly relates to a method of producing an embossed or pleated wall whose base pattern comprises two adjacent dihedrons, one concave and the other convex, whose contour of the faces is a trapezium and whose edges are in the extension of one another and have collinear planar projections, according to which a embossing blank is printed on a flat strip by stamping, the strip is forced to a gradual decrease in its dimension taken perpendicularly. to the aforementioned plane projection of the ridges until reaching a determined threshold of resistance to deformation and then proceed to a controlled progressive unfolding of the structure until the desired thickness is obtained.

The work (displacement force) developed during the lateral compression of the band has the effect of restoring the faces of the dihedrons and reducing the angles of the folds. One can think that this work of compression generates a deformation also distributed on all the cross of the band. It is, however, likely that the heterogeneities of the material due to its manufacture and initial milling treatment disturb the regular distribution of the deformation work. As a result, one area may be deformed faster or earlier than that produced elsewhere. But as soon as a deformation occurs, the kinetics of the deformation of this current zone is such that it increases the heterogeneity of the dis- the deformation energy and total deformation (crushing of cells) of one area can be achieved while others have remained virtually intact. In order to ensure the regular distribution of the deformations during folding, the method of the invention proposes to carry out a folding "block" or at least an equivalent of the latter, determined for example by the moment when the force resistant Compression increases abruptly, thus forming the signal of the state of the product in which folding is practically impossible to continue. It is thus certain that each fold is similar to its neighbor in terms of its internal stresses, the folded product being substantially homogeneous.

The unfolding phase therefore intervenes on a homogeneous product which constitutes a guarantee of the regularity of its unfolding.

During the bending phase, the regularity of the reliefs obtained in terms of their shape and their distribution in the band will be improved by maintaining the band during the compression inside a compression tunnel of the thickness of the wall, formed of two diverging plates whose spacing at a given transverse level is a function of the rate of shrinkage of the band at this same level. The role of the compression plates is first of all to control the global buckling of the product and by limiting the deformation in the initial zones (the summits of the reliefs abut against the plates), to improve the transmission of forces through the zones in the deformation is blocked in the direction of the zones still deformable.

The unfolding efforts will be achieved by driving the folded product at two points of its path at different speeds. Indeed, folding, leading to an increase in the thickness of the strip, produces a decrease in its width but also a decrease in its length, that is to say, if the product is running a speed of travel upstream of the folding greater than the speed downstream of the latter. Thus, the unfolding can be achieved by causing a downstream drive of the product at a higher speed than that of moving the folded product to the maximum leading to longitudinal stretching, transverse expansion and a decrease in the thickness of the strip. The subject of the invention is also a shaping device for implementing the above method, on a strip moving in a given direction, which comprises from upstream to downstream:

a stamping station of a final relief blank for making a repetition of the basic pattern over the entire strip so that the edges of the dihedrons of each pattern are oriented parallel to the direction of travel of the strip in the device of conformation,

a station for lateral compression of the strip perpendicular to its direction of travel,

a station for longitudinal stretching of the folded strip.

The compression station comprises two diverging plates for compressing the thickness of the strip and lateral means, located at the level of the diverging plates, to constrain the banks of the strip to approach one another.

The aforesaid lateral means comprise convergent fixed or moving surfaces forming a bottleneck for the band. The strip is then forced into the funnel formed by the plates and the converging surfaces, accompanied by the lateral surfaces if they are movable and by a set of lateral calibration rollers, at the exit of this compression station. The stretching station has two pin rollers at the exit of the compression station which impose a speed to the scroll of the product and two downstream nip rollers, which impose a speed of travel of the product greater than that of the upstream nip rollers so as to create a transverse expansion of the product during a partial unfolding generated by these relative speeds.

Downstream nip rollers serve as final cell conformers at the same time.

Between the two nip rolls, the deflection station has a set of compression plates for the thickness variation (thinning) of the band. These plates converge in the direction of travel of the band while the space between them flares out to also control the widening of the band resulting from its stretching.

The invention will be better understood during the description given below of an exemplary embodiment with some variants.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will be made to the accompanying drawings in which:

FIG. 1 is a view of the basic pattern, known in itself, of the wall according to the invention,

FIG. 2 is a diagrammatic plan view of a device for implementing the method of the invention,

FIG. 3 is a longitudinal sectional diagram of the device of FIG. 1,

- Figure 4 illustrates in a partial diagram a detail of the embodiment of the device of the invention.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, there is shown in perspective, relatively flat or grazing, an example of a basic pattern of pleating or embossing of a metal sheet to be produced according to the method of the invention. This pattern consists of two adjacent dihedra, one concave and one convex. The dihedron 1 has two faces Ia and Ib whose intersection defines an edge 3. Similarly, the dihedron 2 has two faces 2a and 2b whose intersection defines the edge 4. The contour of the faces here is a parallelogram. The line of intersection of the faces la and 2a is denoted 5 and that of the faces Ib and 2b is denoted 6. They constitute the crest line of the dihedrons 1 and 2 which extends in a direction transverse to the direction of the edges 3 and 4 whose projections on a horizontal plane P, that is to say that of the sheet before deformation, are collinear. The pattern therefore has a preferred direction D, that of the edges of all the dihedrons parallel to the edges 3 and 4. This pattern is more or less pronounced. It should already be noted that if the contour of the faces is not a parallelogram but a trapezium whose bases are collinear, the pattern resulting from the embossing of the sheet will no longer be flat but will have a longitudinal curvature. Similarly, if the edges of the dihedra, defined above as extending in a preferred direction, have projections in the plane which are not quite collinear, the final pattern may present a curvature in the transverse direction of the plane. produced, around the direction D. According to the invention, it begins by performing a stamping blank of a plastic sheet capable of being plastically deformed from this first operation. When treating separate sheets, this stamping can be achieved by two indentations closing one on the other with the sheet between them, whether these prints are planar or not. To process a continuous sheet material 10, resulting for example from a spool, this stamping will be carried out as illustrated in FIGS. 2 and 3, for example by means of rollers 11 whose surface is equipped with reliefs adapted to continuously form the spool. imprint of the blank in the sheet that they pinch. The imprint of the blank is the repetition of the basic pattern of Figure 1 to cover the entire surface of the sheet with the direction of the edges 3 and 4 in the direction of advance D of the sheet during its treatment.

On leaving this first station, the band 10 has a width L. According to the method of the invention, the band undergoes a transverse contraction, perpendicular to the direction D, in a processing station 12. The edges of the band 10 with its embossed reliefs are forced to approach by the lateral sliding surfaces 13a and 13b. This approximation leads to a recovery of the faces 1a, 1b, 2a, 2b of each pattern with a progressive accentuation of the folding until the increase in the thickness of the embossing of the wall is such that it comes into contact with two plates 14a and 14b of contention of this thickness, diverging in the direction of movement of the strip. The relationship between the convergence of the surfaces 13a and 13b to the divergence of the plates 14a and 14b is of the type:

Ei = f ((Li-L) / Li), with L ₇ the width of the band at the entrance of the treatment station 12, Li the width of this band at a distance i of the input of the station 12 and Ei , the value of the spacing of the two plates 14a and 14b at the distance i from the entrance of the station 12.

It is not outside the scope of the invention to provide non-planar plates 14a and 14b for driving, for example, the formation of an embossed wall whose thickness is variable along its width (in the form of bulging or diabolo-shaped for example). The arrows F of FIG. 3 illustrate the possibility of varying the degree of divergence between the walls 14a and 14b, thus the final thickness of the embossed wall that will be produced therefrom. The process of lateral narrowing of the band is also accompanied by a decrease in its longitudinal dimension. This translates into a speed in the post 12 going down.

The surfaces 13a and 13b can be fixed or movable and their convergence adjustable according to the thickness that is desired. In the case of mobile surfaces 13a, 13b, it may be useful to provide them in several sections so as to give them a clean speed less than for example that of the upstream band to account for the decrease in the longitudinal dimension Of the band.

The width Ls of the band at the exit of station 12 is close to the minimum that it can take. This minimum width Lm is that obtained at the output of a set of calibrating rollers 15a, 15b which perfect the folding of the band by imposing a final lateral compression to obtain a folding "block" or almost every dihedron.

A first pair of horizontal pinch rollers lβa, 16b imposes a running speed on the band which is the output band of the calibration rollers. These rollers constitute the entrance of the unfolding station 17 of the installation. It comprises a set of two convergent plates 18a, 18b which, with lateral surfaces 19a, 19b therebetween, make it possible to control the expansion of the strip under the effect of a stretching force in the direction D of travel at by means of a second set of nip rollers 20a, 20b driven at a speed greater than that of the rollers 16a, 16b. The difference in speed and the geometry of the restraining surfaces of the station 17 are related to the degree of expansion of the strip both in length and in width as well as with the decrease in its thickness, these dimensional modifications resulting from the cell opening caused by stretching. The embossed strip 21 from the station 17, beyond rollers 20a, 20b has uniform mechanical properties as far as the rollers 20a, 20b carry reliefs which rectify and standardize the cells of the embossed web. In the case of a band that affects one or the other or a combination of the two aforementioned curvatures, the plates of the treatment stations 1 and 17 will have surfaces facing each other which will be adapted to the progressive form taken by the band during its folding or unfolding.

Claims

1. A method of producing an embossed or pleated wall whose basic pattern comprises two adjacent dihedrons (1,2), one concave and the other convex, whose contour of the faces (la, Ib, 2a, 2b ) is a parallelogram and whose edges (3,4) are in line with each other and have projections in a substantially collinear horizontal plane (D), characterized in that it is printed on a flat strip ( 10) by embossing an embossing blank, in that the band is constrained to a gradual decrease in its dimension taken perpendicularly to the aforesaid plane projection of the edges until reaching a determined threshold of resistance to deformation and in that a controlled gradual unfolding of the strip thus deformed until the desired thickness is obtained.

2. Shaping device for implementing the method according to the preceding claim on a strip (10) moving in a given direction (D), characterized in that it comprises from upstream to downstream: - a stamping station (11) ) of a blank of the final relief to make a repetition of the basic pattern over the entire band so that the edges of the dihedrons of each pattern are oriented parallel to the direction of scrolling

(D) of the web in the shaping device; - a lateral compression station (12, 15a, 15b) of the web perpendicular to its direction of travel (D),

- a station (lβa, lβb, 17, 20a, 20b) of longitudinal stretching of the folded strip.

3. Shaping device according to claim 2, characterized in that the compression station comprises two diverging plates (14a, 14b) for compressing the thickness of the strip and convergent surfaces (13al3b) fixed or movable, forming a bottleneck for the side means strip, located at the diverging plates, to constrain the banks of the band to bring one closer to the other.

4. Device according to claim 3, characterized in that it comprises, at the outlet of the compression station (12), a set of lateral calibrators rollers (15a, 15b).

5. Device according to one of claims 2 to 4, characterized in that the stretching station comprises two pinch rollers (16A, 16b) at the outlet of the compression station, which impose a speed to scroll to the strip and two downstream pinch rollers (20a, 20b), which impose on the web a higher running speed than the upstream pinch rollers so as to create a longitudinal and transverse expansion of the web and a decrease in its thickness, resulting from an unfolding partial generated by these relative speeds.